vp8 is better for low bandwidth/small stuff
Why is its frame rate 20.6 fps?

Something is definitely wrong with they way these videos are encoded.
Discussion
I use Adobe Media encoder and choose the Twitter 720p default encoding, it usually produces the best results and keeps the file size low.
well, i'm just gonna say that you can do this without buying some adobe thing. ffmpeg is very solid
Hard for me to give up my Creative Cloud subscription, I know Adobe sucks, but I’ve been using it forever.